JP3451690B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation which is excellent in solder heat resistance and bending strength.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical characteristics, adhesiveness, etc., and can be given various characteristics by blending formulation, so they are used as industrial materials such as paints, adhesives and electrical insulation materials. Has been done.

For example, as a method of sealing electronic circuit parts such as semiconductor devices, hermetic seals made of metal or ceramics and phenol resin, silicone resin, etc. have hitherto been used.
Resin encapsulation with an epoxy resin or the like has been proposed. However, resin sealing with an epoxy resin is mainly used from the viewpoint of the balance of economy, productivity and physical properties.

In recent years, densification and automation have also been promoted in mounting components on a printed circuit board. Instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the substrate, components are soldered to the surface of the substrate. "Surface mounting method" has become popular. Along with this, the package is shifting from the conventional DIP (dual in-line package) to a thin FPP (flat plastic package) suitable for high-density mounting and surface mounting.

With the shift to the surface mounting system, the soldering process, which has not been a problem so far, has become a big problem. In the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process, but in the surface mounting method, the entire package is immersed in a heating medium and heated. As the soldering method in the surface mounting method, immersion in a solder bath, heating with a saturated vapor of an inert gas (vapor phase method), infrared reflow method, etc. are used. In either method, the entire package is heated to a high temperature of 210 to 270 ° C. It will be heated. Therefore, the package sealed with the conventional sealing resin has a problem that the resin part is cracked during soldering or peeling occurs between the chip and the resin, which reduces reliability and cannot be used as a product. Occurs.

The occurrence of cracks in the soldering process is
It is said that the moisture absorbed between the post-curing and the mounting process explosively vaporizes and expands during soldering heating.As a countermeasure against this, the post-cured package is completely dried and sealed. The method of storing and shipping is used.

Various improvements have been made to the sealing resin. For example, a method of blending a phenol aralkyl resin as a curing agent (JP-A-59-67660) and a method of blending a trifunctional phenol-based curing agent (JP-A 1-1712).
No. 32) is proposed.

On the other hand, when a semiconductor is sealed with an epoxy resin, the coefficient of linear expansion of the epoxy resin is considerably larger than that of the semiconductor, so that thermal stress is applied to the semiconductor element due to temperature changes, which causes aluminum wiring. There is a problem in that the current is leaked by sliding, or cracks are generated in the passivation film or the sealing resin itself, which lowers reliability.
In order to solve this problem and reduce the stress of the sealing resin, it is effective to lower the linear expansion coefficient and the elastic modulus of the sealing resin.

In order to lower the linear expansion coefficient of the sealing resin,
A method of selecting the type of filler and a method of highly filling the filler are known.

Further, in order to reduce the elastic modulus of the sealing resin, it is effective to add an elastomer component. For example, a method of adding silicone rubber, carboxyl group-modified nitrile rubber, polystyrene block copolymer, etc. JP-A-60-18145, JP-A-58-21921
No. 8, JP-A-59-96122, JP-A-58.
-108220, JP-A-59-75922, JP-A-60-1220).

[0011]

However, the method of enclosing the dry package in the container has a drawback that the manufacturing process and the handling work of the product are complicated and the product price is high.

[0012] Further, resins improved by various methods have been gradually effective, but they are still insufficient. A method of blending a conventional phenol aralkyl resin as a curing agent (JP-A-59-67660) and a method of blending a trifunctional phenol-based curing agent (JP-A-1-1).
No. 71232) is effective in preventing cracks in the resin portion during soldering, but when a large chip is used,
There is a problem that the interface between the chip and the resin peels off and the moisture resistance reliability decreases.

On the other hand, in order to lower the elastic modulus of the sealing resin, a method of reducing the stress of the epoxy resin by adding an elastomer component (Japanese Patent Publication No. Sho 60-18145).
JP-A-58-219218, JP-A-59-961
No. 22, JP-A-58-108220, JP-A-59-75922, and JP-A-60-1220), increase of the addition amount causes mold stains and deterioration of fluidity. Therefore, the addition amount was limited, and sufficient stress reduction could not be achieved.

It is an object of the present invention to solve the problem of peeling of the interface between the chip and the resin, which occurs in the soldering process, of a package using such a large chip and suppress the occurrence of cracks, that is, a semiconductor encapsulation having excellent solder heat resistance. An object is to provide a stopping epoxy resin composition.

[0015]

Means for Solving the Problems The present inventors have found that the addition of a curing agent having a specific structure achieves the above-mentioned object and that an epoxy resin composition meeting the purpose can be obtained. The invention was reached.

That is, the present invention relates to an epoxy resin (A),
An epoxy resin composition comprising a curing agent (B) and a filler (C), wherein the curing agent (B) has the following general formula (I):
The epoxy resin (A) contains a phenol compound having a skeleton represented by the following formula (I) as an essential component.
Epoxy resin (a1) represented by I) as an essential component
It is an epoxy resin composition for semiconductor encapsulation, characterized in that the content of the filler (C) is 86 to 95% by weight of the whole.

[Chemical 3] (In the formula, each R ¹ represents a hydrogen atom, an alkyl group, a phenyl group, a benzyl group or a cyclohexyl group.)

[Chemical 4] (However, R ^{2 to} R ⁹ represent a hydrogen atom, a C ^{1 to} C ⁴ lower alkyl group or a halogen atom, and OG represents a 2,3-epoxypropoxy group.)

The structure of the present invention will be described in detail below.

The epoxy resin (A) in the present invention essentially comprises the epoxy resin (a1) represented by the above formula (II).
Contains as a minute. Other epoxy resins include:
Although it is not particularly limited as long as it has two or more epoxy groups in the molecule, a polyglycidyl ether type epoxy resin of polyfunctional phenol is usually used. Specific examples of polyglycidyl ether type epoxy resins of polyfunctional phenols include various novolak type epoxy resins such as cresol novolac type epoxy resins and phenol novolac type epoxy resins, bisphenol A type epoxy resins, and bisphenol F type epoxy resins. Of these epoxy resins, a cresol novolac type epoxy resin is usually preferably used from the viewpoint of moisture resistance reliability, heat resistance and productivity.

In the present invention, both the epoxy resin (a1) represented by the above formula (II ) as the epoxy resin (A) and the epoxy resin (a2) represented by the following general formula (III) are used. It is more preferable to contain as an essential component. Epoxy resin (a1) and (a
By containing an epoxy resin having a bifunctional and rigid skeleton as in 2), the effect of preventing the occurrence of cracks in the soldering process is further improved.

[Chemical 5] (However, two of R ¹⁰ to R ¹⁷ is a 2,3-epoxypropoxy group and the remainder represents a hydrogen atom, a lower alkyl group or a halogen atom C1 -C4.)

Preferred specific examples of the epoxy resin (a ₁ ) in the present invention include 4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3).
-Epoxypropoxy) -3,3 ', 5,5'-tetramethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetramethyl-2
-Chlorobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl-
2-bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetraethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3, 3 ', 5,5'-tetrabutylbiphenyl and the like can be mentioned, and 4,4'-bis (2,3-epoxypropoxy) biphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 Particularly preferred is', 5,5'-tetramethylbiphenyl.

Further, preferred specific examples of the epoxy resin (a ₂ ) in the present invention include 1,5-bis (2,3-epoxypropoxy) naphthalene and 1,5-
Bis (2,3-epoxypropoxy) -7-methylnaphthalene, 1,6-bis (2,3-epoxypropoxy)
Naphthalene, 1,6-bis (2,3-epoxypropoxy) -2-methylnaphthalene, 1,6-bis (2,3-
Epoxypropoxy) -8-methylnaphthalene, 1,6
-Bis (2,3-epoxypropoxy) -4,8-dimethylnaphthalene, 2-bromo-1,6-bis (2,3-)
Epoxypropoxy) naphthalene, 8-bromo-1,6
-Bis (2,3-epoxypropoxy) naphthalene,
2,7-bis (2,3-epoxypropoxy) naphthalene and the like, 1,5-bis (2,3-epoxypropoxy) naphthalene, 1,6-bis (2,3-epoxypropoxy) naphthalene, 2 , 7-Bis (2,3-epoxypropoxy) naphthalene is particularly preferred.

The ratio of the epoxy resins (a ₁ ) and (a ₂ ) contained in the epoxy resin (A) is not particularly limited, but in order to exert a more sufficient effect, the epoxy resin (a ₁₎ ), (A ₂ ) in epoxy resin (A)
It is preferable to contain 0% by weight or more, preferably 50% or more, more preferably 70% or more.

In the present invention, the compounding amount of the epoxy resin (A) is usually 3 to 20% by weight, preferably 3 to 15% by weight.
Is. If the content of the epoxy resin (A) is less than 3% by weight, moldability and adhesiveness are insufficient, and if it exceeds 20% by weight, the coefficient of linear expansion becomes large and it becomes difficult to reduce stress, which is not preferable.

The curing agent (B) in the present invention isCeremony
Phenolic compound represented by (Ι) (b)(Maywa Kasei
(R-3, R-4, etc. manufactured by Co., Ltd.)Contains as an essential ingredient
It is very important to. Contains phenolic compound (b)
If there is no soldering heat resistance improvement effect and humidity resistance reliability improvement effect
Not demonstrated.

[0025]

Further, the curing agent (B) in the present invention is preferably used in combination with a bifunctional curing agent other than the above-mentioned phenol compound (b). Preferred specific examples of the curing agent that can be used in combination are 4,4 ′-(1-α-methylbenzylidene) bisphenol, 4,4 ′-(1-methylethylidene) bis (2-methylphenol), 4,4′- Ethylidene bisphenol, 4,4'-cyclohexylidene bisphenol, 4,4 '-(1-α-methylbenzylidene) bis (2-methylphenol), 4,4'-
(1-Methylethylidene) bis (2-allylphenol), 4,4 '-(1-α-methylbenzylidene) bis (2-ethylphenol), 4,4'-(1-methylethylidene) bis (2- Phenylphenol), 4,4 '
-(1-α-methylbenzylidene) bis (2-phenylphenol), 4,4 '-(1-α-methylbenzylidene) bis (2-t-butylphenol), 4,4'-
(1-α-methylbenzylidene) bis (2-allylphenol), 4,4 ′-(cyclohexylidene) bis (2
-Methylphenol), 4,4 '-(cyclohexylidene) bis (2-allylphenol), 4,4'-(cyclohexylidene) bis (2-phenylphenol) and the like, and 4,4'- (1-α-Methylbenzylidene) bisphenol, 4,4 ′-(1-methylethylidene) bis (2-methylphenol), 4,4′-ethylidenebisphenol, and 4,4′-cyclohexylidenebisphenol are preferable. Among them, 4,4 '-(1-methylethylidene) bis (2-methylphenol), 4,
4'-ethylidene bisphenol, 4,4 '-(1-α
-Methylbenzylidene) bisphenol and 4,4'-cyclohexylidenebisphenol are preferred, and 4,4 '-(1-methylethylidene) bis (2
-Methylphenol) and 4,4'-ethylidene bisphenol.

The ratio of the phenol compound (b) contained in the curing agent (B) is not particularly limited, and the effect of the present invention is exhibited if the phenol compound (b) is contained as an essential component. In order to exert a sufficient effect, the phenol compound (b) is usually added to the curing agent (B) in an amount of 5
.About.100% by weight, preferably 20 to 80% by weight.

In the present invention, the content of the curing agent (B) is usually 2 to 10% by weight, preferably 3 to 8% by weight.
Further, the compounding ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is 0.5 to 1.5, especially from the viewpoint of mechanical properties and moisture resistance reliability. 0.8 ~
It is preferably in the range of 1.2.

Further, in the present invention, the epoxy resin (A)
A curing catalyst may be used to accelerate the curing reaction of the curing agent (B). The curing catalyst is not particularly limited as long as it accelerates the curing reaction, and for example, 2-methylimidazole,
Imidazole compounds such as 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyl Tertiary amine compounds such as dimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetra Organometallic compounds such as methoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum and triphenylphosphine, trimethylphosphine,
Examples thereof include organic phosphine compounds such as triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine and tri (nonylphenyl) phosphine. Among them, organic phosphine compounds are preferable, and triphenylphosphine is particularly preferably used, from the viewpoint of moisture resistance. Two or more kinds of these curing catalysts may be used in combination depending on the use, and the addition amount is the epoxy resin (A).
The range of 0.1 to 10 parts by weight is preferable with respect to 100 parts by weight.

As the filler (C) in the present invention, fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber, etc. Among them, fused silica is particularly preferably used because it has a large effect of lowering the linear expansion coefficient and is effective in reducing stress.

The fused silica referred to herein means an amorphous silica having a true specific gravity of 2.3 or less. The production does not necessarily have to go through the molten state, and any production method can be used. For example, a method of melting crystalline silica, a method of synthesizing from various raw materials, and the like can be mentioned.

The particle size of the fused silica is not particularly limited,
99-50% by weight of crushed fused silica having an average particle size of 10 μm or less and spherical fused silica (c ₁ ) 1-having an average particle size of 4 μm or less
Fused silica consisting of 50% by weight, 99-50% by weight of spherical fused silica (c ₂ ) having an average particle size of 25 μm or less and 1-50% by weight of spherical fused silica (c ₃ ) having an average particle size of 7 μm or less
The fused silica composed of (1) is preferably used because it has a great effect of improving the solder heat resistance. Among them, spherical fused silica (c ₂ ) having an average particle size of 25 μm or less, particularly 10 μm or more and 20 μm
The following spherical fused silica 99 to 50% by weight and average particle size 7 μ
m or less of spherical fused silica (c ₃ ), particularly 0.1 to 6 μm of spherical fused silica 1 to 50% by weight, especially 1 to
The average particle diameter of the spherical fused silica (c ₃ ) is 30% by weight, and is smaller than the average particle diameter of the spherical fused silica (c ₂ ).
The average particle size as used herein means a particle size (median size) with a cumulative weight of 50%, and when two types of abnormally crushed or spherical fused silica having different average particle sizes are used together, the mixture is crushed or spherical. It means the average particle size of fused silica.

In the present invention, the proportion of the filler (C) is 86 to 95% by weight of the whole from the viewpoint of moldability and low stress. Fused silica is preferred as the filler (C).

In the present invention, it is preferable in terms of reliability that the filler is surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, silane coupling agents such as epoxysilane, aminosilane, mercaptosilane and the like are preferably used.

The epoxy resin composition of the present invention includes a halogen compound such as a halogenated epoxy resin, a flame retardant such as a phosphorus compound, a flame retardant aid such as antimony trioxide, a colorant such as carbon black and iron oxide, and a silicone rubber. , Olefin copolymers, modified nitrile rubber, modified polybutadiene rubber, modified silicone oil and other elastomers,
Thermoplastic resins such as polyethylene, long-chain fatty acids, metal salts of long-chain fatty acids, esters of long-chain fatty acids, amides of long-chain fatty acids, mold release agents such as paraffin wax, and crosslinking agents such as organic peroxides are added arbitrarily. can do.

The epoxy resin composition of the present invention is preferably melt-kneaded, for example, by known kneading methods such as Banbury mixer, kneader, roll, single-screw or twin-screw extruder and cokneader. Manufactured.

[0037]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition,% in an Example shows weight%.

Examples 1 to 7 and Comparative Examples 1 to 9 The components shown in Tables 1, 2 and 3 were dry blended with a mixer in the composition ratios shown in Table 4. The mixture was heated and kneaded for 5 minutes using a mixing roll having a roll surface temperature of 90 ° C., cooled and pulverized to produce an epoxy resin composition for semiconductor encapsulation.

This composition was molded by a low pressure transfer molding method under the conditions of 175 ° C. × 2 minutes and 180 ° C. ×
Post cure was carried out under the condition of 5 hours, and the physical properties of the respective compositions were measured by the following physical property measuring methods.

Solder heat resistance: 160 pin with a chip size of 12 × 12 mm and a simulated element having Al vapor deposited on the surface
20 QFP are molded and post-cured, 85 ℃ / 8
IR of maximum temperature 245 ℃ after humidified at 5% RH for 120 hours
After heat treatment in a reflow furnace, the presence or absence of peeling between the chip and the resin interface was examined with an ultrasonic flaw detector. As the failure rate, the rate of QFP in which peeling occurred was determined.

Bending test: A three-point bending test was carried out using a material size of 120 × 12.7 × 6.35 mm with a fulcrum distance of 100 mm and a strain rate of 3 mm / min to obtain bending strength and bending elastic modulus.

Table 4 shows the results of these evaluations.

[0043]

[Table 1]

[Table 2] As shown in Table 4, the epoxy resin compositions of the present invention (Examples 1 to 7 ) are excellent in solder heat resistance, humidity resistance reliability and low stress resistance. In contrast to the specific Comparative Examples 1-9, the soldering heat resistance, moisture resistance reliability are inferior either low stress property.

[0044]

The epoxy resin composition for semiconductor encapsulation of the present invention is excellent in solder heat resistance, moisture resistance reliability, and mechanical properties because the curing agent contains a polyfunctional curing agent having a specific structure.

Continuation of front page (56) Reference JP-A-63-183918 (JP, A) JP-A-61-62519 (JP, A) JP-A-55-3500 (JP, A) JP-A-58-198526 (JP , A) JP-A-1-249826 (JP, A) JP-A-5-259315 (JP, A) JP-A-4-325517 (JP, A) JP-A-4-270724 (JP, A) JP-A 55-60520 (JP, A) JP-A-61-91218 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 59/00-59/72 C08L 63/00-63 / 10 H01L 23/29 H01L 23/31

Claims (2)

(57) [Claims] 1. An epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and a filler (C), wherein the curing agent (B) is represented by the following general formula (I). containing phenolic compound having a skeleton that is as an essential component, the d
The epoxy resin (A) is represented by the following general formula (II)
An epoxy resin composition for semiconductor encapsulation , which contains a xy resin (a1) as an essential component and the proportion of the filler (C) is 86 to 95% by weight of the whole. [Chemical 1] (In the formula, each R ¹ represents a hydrogen atom, an alkyl group, a phenyl group, a benzyl group or a cyclohexyl group.) (However, R ^{2 to} R ⁹ represent a hydrogen atom, a C 1 to C 4 lower alkyl group or a halogen atom, and OG represents a 2,3-epoxypropoxy group.) 2. A semiconductor device which is encapsulated with the epoxy resin composition according to claim 1.